Psion Chess is programmed by Richard Lang, a computer chess champion in the 80s and programmer of some of the most advanced dedicated chess computers of the epoque. The Atari ST version of Psion Chess is said to be a mildly modified version of his "Amsterdam program" which won the 1985 world computer chess championships.
Gamewise, Psion Chess has both 2D and fixed-perspective 3D views of the board, visible both from the black and white sides, a full range of handicaps, move suggestions, solutions for mate problems up to 10 levels, remi offers and most other options a demanding chess player can ask for. A library of 50 master parties is also available for viewing.
The Atari ST version has a ranking of 1960, whereas the Mac version has been rated at 1793 over 80 parties.